Bearing



April 4, 1953 A. H. BEEBE, R 2,635,020

BEARING Filed Aug. 1, 19'50 I N VEIV TOR. flzzazzh M .3 eahz, .7?

' crankshaft of internal-combustion engines.

' essentially noncorrosive in :hot lubricating :oil,

Patented Apr. 14, 1953 UNITED? STATES? PATENT OFFIGE'Z.

to Federal-M ulf Corporation; T-Defil i$;'-Mi0h;ri I a. corporatioxfo'f Michigan AppIica-tionAug'ustiL 1950,"sefiarNofrvflw 6 claims; (Cl. sou-#237.)

v I 1 This invention relates generally to bearings and more j particularly to bearings having *improved*fatigue resistance and which are essen tially stable when operated in an atmosphere or"- bath of -hot lubricating-' oil. 'Bearings ofthis type are widely used, typical examples being the bearings ri 'betweem the connectingrods -andthe overlay-I Ingeneral it can: beF-said' that While I ficie'ritly stable to satisfy vcomm'ercial' srequirew Heretofore, 'it has been conventional 'practice mentsl Nioliel improves stability of theoverlay; to make bearings of this type with a backingof hard metal-ya surface layer or overlay of bearing material which has high fatigue strength andis satisfator' i onto'the copper-lead intermediate layer WhTC nickel makes a relatively: poor bond with the ma termediatelayer, it is harder-than; desirable forand a layer-= intermediate. the backing and :the overlay of metal having-high; heat-conducting characteristics and a medium modulus of -elas-- ticity.-- Allof these metallic-layers are suitably" bonded together over their entire' surfaces.- 1 Steel is universally used for the backing. A suitable lead base alloyhaving five"per"'cent"or moreof tin usually is used'for theoverlayrCopper', sil= Y verjor allo'ys thereof conventionally are 'used as i" the intermediate layer and; of these; copper l'ead alloys generally are preferred? Apparentlyjthe tin'in the'overlay'i's largelyresponsible for the resistanceof""the bearin'gto corrosion""'and" some difiicuity' hasbeen experienced with thetin diffusing 'fromthe overlay into/J the intermediate layer. Difiusion of.the"tin' is i particularly""prOIIOunCed if "the intermediate 3O r purpose. layeris the1preferred copper lead alloy;si Loss of tin I from' 'the' overlay" progressively reducesrthe resistance of the bearings ;to corrosion and thus? considerably shortens the useffil life of the bear i' ings. Also, it is genera'lly recognized that the: difiused tin particles:- form 'iindes'irable metallic compounds of copper-tin 'on -t-her surface of the intermediate layer. 7

.These phenomena have been recognized by the; industry, and meanshas been-'suggestflifor-pre venting difiusion --'of :the-=-tin'.:- For example Luetkemeyer et-a1.-- suggest; in Patent=- No:- 2,45,9;l 72, issued danuary lfif 1949; that a barrier layer of nickel, cobalt, silver, or iron be interposed between the overlay and the: intermediate-layer. Apparently these barrier metalsim some manner-f retard:,diffusion of Mn from the overlay'into-the copper-leaddntermediate layer;

While it is true that -the: four metals hereto l foretusedrforthebarrier layer at .leastz-retarddi fusion; of tin from ith'e overlay;=-rnot .OIIB O'f Ethesec metals is entirelysatisfactory;both fromaa com'. mercial and'a functionaixpointof view: Each of; the's'e metalsnhas certainciecogniz'edsdisadva conductivit -Iron"=-is "perhapsvithe best=of the the overlay, iibllti it has all" thewdisadvantages 3 noted in eonnectio'n with'nickel'.

ha"s- -recognized and is seeking "a solution to the tioiis 'to 'the problem have notxbeementirely satis-' factory.

I have-noweiscovered'a metallic mediathat is preeminently satisfactory as a barrier material-Tram a ooin'mercial 'poi-nt of vie'w-"and that is markedly superior functionally to any of silver, nickel-,-cobalt; -or--iron-heretof-ore used for this lay and the intermediate layer; establishes' a At the same time; disadvantagesinherentdn the pose-fare avoided. Brass is an alloyof copper-and zinc: both "of "which elementsf' areavailable in large Quantities." It is easilyielectroplated 'to a layera'nd thelead-tin'overlay? It is not objectionably hard, andits' heatconductivity is ade-- quate forthe purpose of this inventioni- Further,

Thus, the suitabi-lity-oi brass as a barrier layer Specifically, I have disoovered thatbrass, When-used as abarrier -between-theover' pensive t'o -be commercially practicablez-i In -ad:-' dition andperhaps -more important; silver and! cobalt are considerably less 'efiective -than' nickel r and iron in preventing diffusion of tin fron'r-the si1ver-anaoba1tmaybe operative-to retard diffus'ion of -tin; theydo not renderthe-ioverl-ay suf-- 10 hovv ever, in 'praetic'e 'it is difficult to eleotroplate ofte'n fr is i quiteporous"; Further; I

itsihtriddfise; and it has a relatively; low heat' four metals mentionedfor promoting stability of- Freinthe foregoingi-it is apparentthat the art problemsetforth above 'but that proposed solu-- good. bond and promotes stability of th'overl'ay.

a several metals previously suggested for this bur:

desiredwhi'cknes's"andforms "an excellent-bond 40 sbetw'e'en "the? porous ,co per lealr- "intermediate the copper portion-of the brass barrier 'layer rappareritly does not form undesirable metall-ie compounds with-th tiri z thenoverlay layer? s i is entirely unexpected -in vieii fif the generally know mtact that iwheni the lead tin overlay is .25O -.*applied:-direotly to the copper' lead intermediate layen -tin -particles='difi-use-- from the: overlay a and 4 formz undesirable compounds withzthez copperi-iof thr copperel'ead intermediatelayers 'Thisi-p-robe 1 lem is recognized ands-dealt withiat some length tag'esz -i-Forea ample;zsilver and cobalt arertoowx zzwin the-Luetkemeyer et :aL patent supra/1931i; is note known why the undesirable copper-tin compounds are not formed when brass is used as the barrier layer, but it would appear that the presence of zinc in the barrier layer has some effect on the two metals which prevents formation of the undesirable compounds.

The accompanying drawing shows a semicircular bearing illustrating the novel features of my invention.

In the drawing:

Fig. 1 is a top plan View of the bearing and Fig. 2 is an enlarged, transverse sectional view taken on the line 2--2 of Fig. 1.

With particular reference to the drawing, the numeral l designates the conventional steel or other hard metal backing of the bearing. In addition, the bearing has the usual lead-tin overlay l2 and the copper lead intermediate layer I4 which is bonded to the backing l0 between the latter and the overlay. According to the present invention, a brass barrier layer It is interposed between and bonded over its entire surface to the overlay 12 on the one side and the intermediate layer [4 on the other.

The following test is typical of a number of tests which were made comparing brass as a barrier material with a large number of metals including the four metals recommended by Luetkemeyer et a1. Except for the barrier, all of bearings used in the tests were identical having steel backing layers, copper-lead intermediate layers, and lead-in overlays combined and correlated as shown in the drawing. The bearings Were tested in a conventional deflected shafttype bearing testing machine, and they were subjected to the same load for approximately the same length of time. A chemical analysis of the leadin overlay of each hearing was made before and after testing to determine loss of tin from the overlay. For purpose of comparison, a hearing was tested which was identical to the ones described above except that it had no barrier layer at all. The following results were observed:

the Overlay Brass (zinc 20%, copper 80%) N" kel 10 No intermediate layer In practice I have found that the brass barrier layer I6 is effective in various thicknesses. A barrier layer approximately 0.0001 inch is satisfactory, but there is nothing to indicate that this is critical. Apparently the thickness of the in termediate layer I4 is determined only by the exigencies of the particular situation. The barrier layer [6 may be applied by well-known electroplating or equivalent processes.

The brass barrier layer !6 preferably comprises from to 35% zinc and from 65%85% copper. These ranges are not necessarily critical, but they do represent optimum proportions. As the amount of zinc is reduced below 15% there is a progressive decrease in the barrier effect, or, conversely, a progressive increase in the diffusion of tin from the overlay. As the amount of zinc is increased above 35%, the adhesion effect or bond between the brass layer and the intermediate layer becomes progressively poorer. Thus, as the proportion of zinc is varied in either direction beyond the range given, there is a gradual loss of the benefit of this invention. However, it will be appreciated that some benefits can be obtained even though zinc is present in proportions outside the preferred range.

While the present invention is not particularly concerned, except as noted above, with the nature or physical dimensions of the bearing apart from the barrier layer, bearings having the following characteristics have been found to be satisfactory. It is to be understood, however, that these characteristics are given merely by way of illustration and not by way of limitation.

1. Steel backing layer, 0.04%-0.20% carbon, de-

pending upon the application and method of manufacture of the bearing 2. Copper-lead intermediate layer, 21 %-2'7% lead; '73%-79% copper 3. Brass barrier layer,

15%-35% zinc 4. Lead-tin overlay, 8%-12% tin; 88%-92% lead The following is a specification of a typical bearing made and tested during development of this invention.

65 copper;

Copper cyanide 50 grams per liter Zinc cyanide '75 grams per liter Sod um cyanide grams per liter Sod1um carbonate 30 grams per liter Sodium potassium tartrate 45 grams per liter Ammonium hydroxide (conc.) 5 ml. per liter Temperature 35-50 C. Current density 20-50 amp. per sq. ft. Time for 0.0001 inch 2-4 minutes After the brass layer It has been deposited on the copper-lead intermediate layer I 3 the hearing is rinsed, acid dipped, rinsed again and the lead-tin overlay l2 then plated on the barrier layer [6 in the conventional way.

Having thus described the invention, I claim:

1. A composite bearing comprising a steel backing layer, an intermediate layer of copper-lead alloy on said backing layer, a surface layer of a tin containing bearing alloy metal, and a barrier layer of brass between said intermediate layer and said surface layer, all of said layers being uniformly bonded to each other over their entire surfaces.

2. A composite bearing comprising a steel backing layer, an intermediate layer of copper-lead alloy, a surface layer of bearing metal alloy containing at least 5% tin, and a barrier layer of brass between said intermediate layer and said surface layer, all of said layers being uniformly bonded to each other over their entire surfaces.

3. A composite bearing comprising a steel backing layer, an intermediate layerof copper-lead alloy on said backing layer, a surface layer of a tin containing bearing alloy metal, and a barrier layer of brass approximately .0001" thick between said intermediate layer and said surface layer, all of said layers being uniformly bonded to each other over their entire surfaces.

4. A composite bearing comprising a steel backing layer, an intermediate layer of copper-lead alloy, a surface layer of bearing metal alloy containing at least 5% tin, and a barrier layer of brass containing at least 15% and not more than 35% zinc between said intermediate layer and said surface layer, all of said layers being uniformly bonded to each other over their entire surfaces.

'5. A composite bearing comprising a hard metal backing layer, an intermediate layer of copper-lead alloy on said backing layer, a surface layer of tin containin bearing-alloy metal, and a barrier layer of brass between said intermediate layer and said surface layer, all of said layers being uniformly bonded to each other over their entire surfaces.

6. A composite bearing comprising a hard metal backing layer, an intermediate layer of high conductivity metal on said backing layer, a surface layer of tin containing bearing-alloy metal, and a barrier layer of brass between said intermediate layer and said surface layer covering the entire surface of said intermediate layer exposed to said surface layer, said brass barrier layer effectively preventing contact between said surface layer and said intermediate layer and inhibiting any tendency for tin to migrate from said surface layer into said intermediate layer.

AUSTIN H. BEEBE, JR.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,303,408 Starker May 13, 1919 2,459,172 Luetkemeyer et al. Jan. 18, 1949 

1. A COMPOSITE BEARING COMPRISING A STEEL BACKING LAYER, AN INTERMEDIATE LAYER OF COPPER-LEAD ALLOY ON SAID BACKING LAYER, A SURFACE LAYER OF A TIN CONTAINING BEARING ALLOY METAL, AND A BARRIER LAYER OF BRASS BETWEEN SAID INTERMEDIATE LAYER AND SAID SURFACE LAYER, ALL OF SAID LAYERS BEING UNIFORMLY BONDED TO EACH OTHER OVER THEIR ENTIRE SURFACES. 